I am new to UltraVNC but not to VNC software in general. I have used RealVNC for a few years now and wanted something a bit more secure. So I am giving UltraVNC a shot.

When I configure the New MS Logon and add myself to the user list and try to connect to the remote computer using my username and password for UltraVNC, I keep getting the error message, "VNC authentication failed!". When I turn off the New MS Logon and just enter the VNC password, I connect every time without any problems.

I am not sure what is wrong with the New MS Logon. I tried it again by adding a different user and password and still cannot connect, but if I turn New MS Logon off and use just the VNC password, I can connect every time without any problems.

The added security of New MS Logon attracts me to using UltraVNC. What can I do to make it work?

Under Windows XP, the ForceGuest registry value is set to 1 by default in the following registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

On a Windows XP computer you must check:If the Guest account is enabled, an SSPI logon will succeed as Guest for any user credentials.If ForceGuest is disabled (set to 0), SSPI will log on as the specified user.If the authtest util gives guest account blocked, an open guest account is detected and ms logon denies all access.

i been looking into making a switch from tight vnc to ultravnc because connecting over the internet needed some more security.

now its works wel when using the server password having ms logon disabeld but when i enable ms logon i get the message "VNC authentication failed!" this ocures whith the ultravnc server running as a service on a windows server 2003 platform which is not part of a domain (so standalone server).

ok so what have a tryed to fix this
after going over these boards i tryed the registry setting
HKEY_LOCAL ....Lsa : forceguest
but it was already set to 0 (changing to 1 didnt help so i just changed it back to 0)
i tryed installing it as a server from the ultavnc server progral (right click on the taskbad icon) whith and whithoud the restricted rights box checkt
al also tryed adding the local administrators group to the ms logon as group 1 (schould not be needed since it says the local administrators have acces by default).
tryed restarting the ultravnc service even rebooted te machine between attempts but no succes.

is there a manual to this that i over lookt? most of whats mentiond is in xp not in server 2k3 (they schould work pritty much similar specialy since its local users authenticating)

i know this might not seem like a big deal, one could say vnc works with its native authentication so why bother. but of from a security standpoint it would be benificial to use ms logon as a aditional layer of security.

Last edited by RedSackles on 2009-10-05 02:30, edited 1 time in total.

i attemted your suggestion but after putting in the username and password of the local administrator i still get the same message "VNC authentication failed!"
adding the local administrators group or a vnc user group (a group i made) or a none existing group dont seem to change this.

I'm getting the same error here, with both new and old MS Logon. I'm trying to reverse-connect an XP server to a Win7 client, both on the same intranet through a router, and not getting anywhere. Using simple uVNC password works smoothly.

The error message gives several possibilities, but I think I've got them all covered, so it must be an MS Logon problem. Too bad, because the increased security is very desirable.

paul1149 wrote:I'm getting the same error here, with both new and old MS Logon. I'm trying to reverse-connect an XP server to a Win7 client, both on the same intranet through a router, and not getting anywhere. Using simple uVNC password works smoothly.

I don't understand.

In reverse connection, there is no authentication, i.e. use neither VNC password, nor MS Logon user+password.